#include "md5.h"

namespace shove
{
namespace hash
{

#define GET_UINT32(n, b, i)                                         \
{                                                                   \
    (n) = (__uint32) ((__uint8*) b)[(i)]                            \
    | (((__uint32) ((__uint8*) b)[(i) + 1]) <<  8)                  \
    | (((__uint32) ((__uint8*) b)[(i) + 2]) << 16)                  \
    | (((__uint32) ((__uint8*) b)[(i) + 3]) << 24);                 \
}

#define PUT_UINT32(n, b, i)                                         \
{                                                                   \
    (((__uint8*) b)[(i)]    ) = (__uint8) (((n)      ) & 0xFF);     \
    (((__uint8*) b)[(i) + 1]) = (__uint8) (((n) >>  8) & 0xFF);     \
    (((__uint8*) b)[(i) + 2]) = (__uint8) (((n) >> 16) & 0xFF);     \
    (((__uint8*) b)[(i) + 3]) = (__uint8) (((n) >> 24) & 0xFF);     \
}

MD5::MD5()
{
}

void MD5::md5_starts(struct md5_context* ctx)
{
    ctx->total[0] = 0;
    ctx->total[1] = 0;
    ctx->state[0] = 0x67452301;
    ctx->state[1] = 0xEFCDAB89;
    ctx->state[2] = 0x98BADCFE;
    ctx->state[3] = 0x10325476;
}

void MD5::md5_process(struct md5_context* ctx, __uint8 data[64])
{
    __uint32 A, B, C, D, X[16];

    GET_UINT32(X[0],  data,  0);
    GET_UINT32(X[1],  data,  4);
    GET_UINT32(X[2],  data,  8);
    GET_UINT32(X[3],  data, 12);
    GET_UINT32(X[4],  data, 16);
    GET_UINT32(X[5],  data, 20);
    GET_UINT32(X[6],  data, 24);
    GET_UINT32(X[7],  data, 28);
    GET_UINT32(X[8],  data, 32);
    GET_UINT32(X[9],  data, 36);
    GET_UINT32(X[10], data, 40);
    GET_UINT32(X[11], data, 44);
    GET_UINT32(X[12], data, 48);
    GET_UINT32(X[13], data, 52);
    GET_UINT32(X[14], data, 56);
    GET_UINT32(X[15], data, 60);

#define S(x, n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define P(a, b, c, d, k, s, t)                          \
{                                                       \
    a += F(b, c, d) + X[k] + t; a = S(a, s) + b;        \
}

    A = ctx->state[0];
    B = ctx->state[1];
    C = ctx->state[2];
    D = ctx->state[3];

#define F(x, y, z) (z ^ (x & (y ^ z)))

    P(A, B, C, D,  0,  7, 0xD76AA478);
    P(D, A, B, C,  1, 12, 0xE8C7B756);
    P(C, D, A, B,  2, 17, 0x242070DB);
    P(B, C, D, A,  3, 22, 0xC1BDCEEE);
    P(A, B, C, D,  4,  7, 0xF57C0FAF);
    P(D, A, B, C,  5, 12, 0x4787C62A);
    P(C, D, A, B,  6, 17, 0xA8304613);
    P(B, C, D, A,  7, 22, 0xFD469501);
    P(A, B, C, D,  8,  7, 0x698098D8);
    P(D, A, B, C,  9, 12, 0x8B44F7AF);
    P(C, D, A, B, 10, 17, 0xFFFF5BB1);
    P(B, C, D, A, 11, 22, 0x895CD7BE);
    P(A, B, C, D, 12,  7, 0x6B901122);
    P(D, A, B, C, 13, 12, 0xFD987193);
    P(C, D, A, B, 14, 17, 0xA679438E);
    P(B, C, D, A, 15, 22, 0x49B40821);

#undef F

#define F(x, y, z) (y ^ (z & (x ^ y)))

    P(A, B, C, D,  1,  5, 0xF61E2562);
    P(D, A, B, C,  6,  9, 0xC040B340);
    P(C, D, A, B, 11, 14, 0x265E5A51);
    P(B, C, D, A,  0, 20, 0xE9B6C7AA);
    P(A, B, C, D,  5,  5, 0xD62F105D);
    P(D, A, B, C, 10,  9, 0x02441453);
    P(C, D, A, B, 15, 14, 0xD8A1E681);
    P(B, C, D, A,  4, 20, 0xE7D3FBC8);
    P(A, B, C, D,  9,  5, 0x21E1CDE6);
    P(D, A, B, C, 14,  9, 0xC33707D6);
    P(C, D, A, B,  3, 14, 0xF4D50D87);
    P(B, C, D, A,  8, 20, 0x455A14ED);
    P(A, B, C, D, 13,  5, 0xA9E3E905);
    P(D, A, B, C,  2,  9, 0xFCEFA3F8);
    P(C, D, A, B,  7, 14, 0x676F02D9);
    P(B, C, D, A, 12, 20, 0x8D2A4C8A);

#undef F

#define F(x, y, z) (x ^ y ^ z)

    P(A, B, C, D,  5,  4, 0xFFFA3942);
    P(D, A, B, C,  8, 11, 0x8771F681);
    P(C, D, A, B, 11, 16, 0x6D9D6122);
    P(B, C, D, A, 14, 23, 0xFDE5380C);
    P(A, B, C, D,  1,  4, 0xA4BEEA44);
    P(D, A, B, C,  4, 11, 0x4BDECFA9);
    P(C, D, A, B,  7, 16, 0xF6BB4B60);
    P(B, C, D, A, 10, 23, 0xBEBFBC70);
    P(A, B, C, D, 13,  4, 0x289B7EC6);
    P(D, A, B, C,  0, 11, 0xEAA127FA);
    P(C, D, A, B,  3, 16, 0xD4EF3085);
    P(B, C, D, A,  6, 23, 0x04881D05);
    P(A, B, C, D,  9,  4, 0xD9D4D039);
    P(D, A, B, C, 12, 11, 0xE6DB99E5);
    P(C, D, A, B, 15, 16, 0x1FA27CF8);
    P(B, C, D, A,  2, 23, 0xC4AC5665);

#undef F

#define F(x, y, z) (y ^ (x | ~z))

    P(A, B, C, D,  0,  6, 0xF4292244);
    P(D, A, B, C,  7, 10, 0x432AFF97);
    P(C, D, A, B, 14, 15, 0xAB9423A7);
    P(B, C, D, A,  5, 21, 0xFC93A039);
    P(A, B, C, D, 12,  6, 0x655B59C3);
    P(D, A, B, C,  3, 10, 0x8F0CCC92);
    P(C, D, A, B, 10, 15, 0xFFEFF47D);
    P(B, C, D, A,  1, 21, 0x85845DD1);
    P(A, B, C, D,  8,  6, 0x6FA87E4F);
    P(D, A, B, C, 15, 10, 0xFE2CE6E0);
    P(C, D, A, B,  6, 15, 0xA3014314);
    P(B, C, D, A, 13, 21, 0x4E0811A1);
    P(A, B, C, D,  4,  6, 0xF7537E82);
    P(D, A, B, C, 11, 10, 0xBD3AF235);
    P(C, D, A, B,  2, 15, 0x2AD7D2BB);
    P(B, C, D, A,  9, 21, 0xEB86D391);

#undef F

    ctx->state[0] += A;
    ctx->state[1] += B;
    ctx->state[2] += C;
    ctx->state[3] += D;
}

void MD5::md5_update(struct md5_context* ctx, __uint8* input, size_t length)
{
    __uint32 left, fill;

    if (!length)
    {
        return;
    }

    left = (ctx->total[0] >> 3) & 0x3F;
    fill = 64 - left;

    ctx->total[0] += (unsigned int)(length <<  3);
    ctx->total[1] += (unsigned int)(length >> 29);

    ctx->total[0] &= 0xFFFFFFFF;
    ctx->total[1] += ctx->total[0] < length << 3;

    if (left && length >= fill)
    {
        memcpy((void*)(ctx->buffer + left), (void*)input, fill);
        md5_process(ctx, ctx->buffer);
        length -= fill;
        input  += fill;
        left = 0;
    }

    while (length >= 64)
    {
        md5_process(ctx, input);
        length -= 64;
        input  += 64;
    }

    if (length)
    {
        memcpy((void *)(ctx->buffer + left), (void*)input, length);
    }
}

static __uint8 md5_padding[64] =
{
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

void MD5::md5_finish(struct md5_context* ctx, __uint8 digest[16])
{
    __uint32 last, padn;
    __uint8  msglen[8];

    PUT_UINT32(ctx->total[0], msglen, 0);
    PUT_UINT32(ctx->total[1], msglen, 4);

    last = (ctx->total[0] >> 3) & 0x3F;
    padn = (last < 56 ) ? ( 56 - last ) : ( 120 - last);

    md5_update(ctx, md5_padding, padn);
    md5_update(ctx, msglen, 8);

    PUT_UINT32(ctx->state[0], digest,  0);
    PUT_UINT32(ctx->state[1], digest,  4);
    PUT_UINT32(ctx->state[2], digest,  8);
    PUT_UINT32(ctx->state[3], digest, 12);
}

string MD5::GenerateMD5(unsigned char* buffer, size_t length)
{
    struct md5_context context;
    unsigned int data[4];

    for (int i = 0; i < 4; i++)
    {
        data[i] = 0;
    }

    md5_starts(&context);
    md5_update(&context, buffer, length);
    md5_finish(&context, (unsigned char*)data);

    return this->toString(data);
}

string MD5::toString(unsigned int* data)
{
    char output[33];

    for (int j = 0; j < 16; j++)
    {
        sprintf(output + j * 2, "%02x", ((unsigned char*)data)[j]);
    }

    return string(output);
}

}
}
